Theres this great site called massdrop.com (registration required) where you can group buy items extremely cheaply. Anyone can suggest a product and after it gets 200 votes, Massdrop will contact a/the distributor to get a group deal. Some people are trying to get full printers up there but I think the site could be great for group buys of filament. Heres the link to the 3D printer filament group, I suggested the Ninjaflex/Semiflex but you can post other filaments as well. Please vote for filament, you can vote for up to 3.